In recent years, engines have been made smaller to enhance fuel economy of automobiles, and along with this, automobiles having an engine to which a supercharger (turbo) is introduced are becoming more popular. Due to the introduction of the supercharger, the temperature around an engine is increased, and highly heat resistant hoses have been increasingly demanded as radiator hoses, air conditioner hoses, or the like.
Meanwhile, as a rubber composition having heat resistance, for example, Japanese Unexamined Patent Application Publication No. 2016-030761 is proposed.
Japanese Unexamined Patent Application Publication No. 2016-030761 describes
a rubber composition for a heat-resistant conveyor belt including:
an ethylene-1-butene copolymer having a Mooney viscosity at 125° C. of 20 or greater; and
an ethylene-propylene copolymer having a Mooney viscosity at 125° C. of 20 or greater and an ethylene content of 40 to 60 mass %;
a mass ratio of the ethylene-1-butene copolymer to the ethylene-propylene copolymer being from 10/90 to 90/10.
In such circumstances, when the inventors of the present technology prepared a rubber composition using Japanese Unexamined Patent Application Publication No. 2016-030761 as a reference and evaluated this, it was found that such a rubber composition may not satisfy heat resistance that has been required for air conditioner hoses for automobiles, and that the adhesion to reinforcing yarn may be low.